The aim of this research was to compare the accuracy of urinary protein/creatinine ratio (PCR) and albumin/creatinine ratio (ACR) in defining optimal cut-off points to rule-out significant proteinuria (>300 mg/24 h) in pregnancy. The secondary outcome measure was to determine the investigation of choice to evaluate proteinuria used by maternity units in the UK. PCR and ACR were calculated on first (PCR1, ACR1) void urine samples of the 24-hour urinary protein collection (24UP). Sensitivity and specificity was calculated for different cut-off points for PCR1 and ACR1 to rule-out significant proteinuria. An online survey was sent to RCOG members questioning them on their investigation of choice to evaluate proteinuria. We concluded from our results that both PCR and ACR are good rule-out tests for significant proteinuria in pregnancy using cut-off points of <20 mg/mmol and <2.5 mg/mmol. PCR is the investigation of choice in 56% of UK units studied.